Zeolite crystal structures have found a wide range of applications within refinery processes and other processes for manipulating petroleum streams. Some zeolite applications are catalytic in nature, while other applications focus on the ability of zeolites to selectively adsorb molecules within a gas stream.
One example of selective adsorption of molecules from a gas phase stream is using a zeolite or another microporous material to remove contaminants from a stream containing hydrocarbons or other small gas phase organic molecules. For example, many natural gas streams contain at least some CO2 in addition to the desired CH4. Additionally, many refinery processes generate a gas phase output that includes a variety of species, such as CH4 and CO2, that are gases at standard temperature and pressure. Performing a separation on a gas phase stream containing CH4 can allow for removal of an impurity and/or diluent such as CO2 or N2 under controlled conditions. Such an impurity or diluent can then be directed to other processes, such as being directed to another use that reduces the loss of greenhouse gases to the environment.
U.S. Patent Application Publication No. 2008/0282885 describes systems and methods for removing CO2, N2, or H2S using a swing adsorption process. One type of adsorbent that can be used in the swing adsorption process is an 8-ring zeolite, such as a DDR type zeolite.